Resistance of chestnut trees to Asian chestnut gall wasp Stehll. 2003 . Stehii. 2006) American and Chmese chest­ Sandra Anagnostakis', Stacy Clark', and Henry McNab' nuts (Cmtanea dellfata and C lIIolhwllla) all appcar to be susceptIbl e to thIS pest (Pa~ ne et al 1976) At present Olere 'The Connecticut Agricultural Experiment StatIOn, arc fe\l predators to stop gall \I asp from mo,ing throughout PO Box 1106, New Haven, CT 06504 Sandra Anagnostakls@ct gov, the range of AmerIcan chestnut trees (Cooper et al.. 2007) Ph 203-974-8498, Fx 203-974-8502 Eggs arc laId In leaf and flo\ler buds. the de,elopll1g galls kill the leaves and !lo\lers. and IIlfestatlons can result In tree ' USDNForest Service, Southern Research Station, Upland Hardwood Ecology and Management Research death 11,e pest \las found 111 northern I tal~ 111 2002. and Work Unit, The University ofTennessee, European chestnut (e sativa) and man' commercIal h~ bnds Department of Forestry, 'Mldhfe, and Fisheries, \lere ll1fested '\lth levels serIOUS enough to result 111 SignIfi­ 2431 Joe Johnson Dr, Knoxville, TN 37996-4563 cant tree mortalit~ (Sartor et al _ 2009) No pcstIcldes arc ' USDA Forest Service, currcntl~ regIstered for control of thIS Insect In 1995. h,­ 1577 Brevard Rd ., Asheville, NC 28806 brid chestIlUts \I ere planted 111 the state of North CarolIna. In cooperatI on \I ith the U.S. Forest ServIce. to test the trees for Abstract. Asian chestnut gal l \lasp (Dryocosmlls kllnplll­ reslstancc to InfestatIon In an area \I here ASIan chestnut gall Ills) \I as Introduced Into GeorgIa (USA) in 1975 and has been \lasp \las present spreadIng north th ro ughout the rangc of American chestnut ~ (Castanea den/Gla) This pest is nO\l present throughout Materials and Methods most of Tennessee. In 2003_ It \las found ncar Cle,eland. 11,e research plot \I as establIshed at 760 m ele, atIon 111 OhIo and has been spreading south from Olere . [n 1995. h~­ the Southern AppalachIan Mountall1s (35 "30·N. 82 '3J"W) bnd chestnuts \I ith C dentata female parents and t\l 0 Ozark about 16 km southwest of Ashe\llle. NC \lhere both chest­ chInquapIn x Chinese chestnut male parents (e ozarkenSIS nut blight disease (caused b~ Cr,lphonecfrla parawlca) and xC mol/I.wma) \lcre planted in North Carolina_ \I herc OllS ASIan chestnut gall (I) kunpllllus) \I ere present 11,e stud, Introduced msect IS nO\l naturalIzed. Of the 93 trees plantcd. sI te \I as located along an cdge of a la rge (>4 hal forest opcn­ 69 surv.i,ed four years. and 36 \lere still surv iving after 14 IIlg that had been cleared of vegetatIon 111 1994 11,e trces sur­ years. 11,e surv iVIng trecs \I crc c,aluated for the prcsence roundIng the stud, sIte \I ere pnmanl~ sca rl et oak (Quercus of ASIan chestnut gall \lasp galls in 2006 and 2009. After coccmea) and \lhIte oak (Q alha). '\lth an und crsto~ of 14 years. the proge n ~ of one male parent had 67% survival red maple (Acer ruhrum) and soumood (Oxydendrulll arbo­ and of the other. 16% surv i, al Among the survivors. 3 I reum)_ scanered root sprouts of Amencan chestIlut (C den­ had no \I asp galls in 2009 and 4 had 10 or fe\ler galls. The tata) \I ere also present. 11,e stud, site \las 0.05 ha. consist­ four female parents (American chestnuts and half-sibs) \lere ing of five ro\lS spaced 3.05 m apart. and trees \Vere spaced assumed to be fully susceptible. so the genes controlling re­ 1.5 m apart \I ithin each ro\l sIstance to infestation cannot be c~10p l asmic . If resistance 11,e female parents of the h~ bnds planted \I ere four dIffer­ IS conferred b) one or t\lO nuclear genes, resistance can cas- ent American chestnut trees Olat \I ere half-sibs. and th e male il~ be transferred into timber chestnuts and orchard chestnut parents (called M I and M2) \lere 1\' 0 dIfferent trees of C cultl\ars. ozarkel1.lls x C lIIol/lsSll1Ia (Ozark chInquapIn crossed \I Ith Chinese chestnu!. the Ozark chll1quapll1 and Chinese chest­ Introduction nut parents of dlese t\lO trees \lere not the same) (Table I)

sian chestnut gall \I asp. Dr),ocosmlls kliriphillis. (Payne and both male parents had good resistance to chestnut blight Aet al. 1976: Rieske_ 2007) has nO\l spread from the disease. The h~ brids were from hand-pollinated crosses state of Georgia. where it was introduced in 1974. to most made in 1993 in Connecticut (seed planted in Apnl 1994). of the southern gro\l ing area of chestnut trees in the United A total of93 seedlings \I ere dug in April 1995 and delIvered Stmes. and to the vicmit) of Cle, eland. OH (Rieske. 2007: (bare-root) to th e plantIng SIt e 111 earh Ma' 1995 . We used a completel, randomI zed expenmental de Ign consIsting of 101 " Annual Report, March 2011 15 single-tree plots and no perimeter buffer ro\\ CompetIng ease on theIr trunks (I e .. one tree had no cankers) and sev­ vegetation In the aCIdIc (pH<5.5) silt) to sand~ loam sedI­ en had dIed to the ground and had large sprouts \\ Ith small ment matenal consIsted mostl) of blackbe~ (Rubus spp.) blIght cankers canes. \\hlch \\ere cut at ground level dunng the late \\lnter In 2006. 36 of the total 53 sunl\Ors had fe\\ (one 10 10) for the first four years of the stud). Most of the seedlIngs or no \\asp galls In 2009. 35 of the 36 sun "ors had fe\\ or had grown to saplIng SIZC by 1999 and had formed a closed no \\ asp galls (Table 2) canop~ that shaded competing vegetation. The trees were examined In the fall of 2006 (Anagnostakis et a1.. 2009) and Discussion 2009, and the presence of chestnut blight disease cankers on ASIan chestnut gall \\ asp has been a senous problem in the trunks and galls on terminal branches \\ere recorded Japan on Japanese chestnut (C crenora) for man~ years. and efforts have been made to select cultivars \\ ith some tol­ Results f erance to the insect. Kotobuki and his colleagues (1984) In 1999.26 of the 44 hybrids with MI , and 43 of the 49 made 26 crosses (770 IOtal progeny) of Japanese cultivars h~ bnds \\lth M2 \\ere still alive. By 2006. 17 of 44 and 36 of chestnut. and rated them for presence of galls. When of 49 sUf\1ved: b~ 2009, the survival rate fell to 7 of 44 and rated after 5 or 6 years. 50% or more of the progen\ of II 29 of 49 respect"el~ for M I and M2 progen~ In 2009. all crosses had"no galls on tree" or "very small number of galls but one of the sun IVOrs had cankers of chestnut blIght dls-

Table 1. Source of the hybrid chestnut trees planted in 1995 in North Carolina in an area where Asian chestnut gall wasp (Oryocosmus kuriphilus) and chestnut blight disease (Cryphonectria parasitical were present.

Female parent' Male parent 1 #Trees planted #Survivors 20 09 American 1 Ozark chinquapin 1 x Chinese 1 6 American 2 Ozark chinquapin 1 x Chinese 1 18 1 American 3 Ozark chinquapin 1 x Chinese 1 20 5 Male parent 2 American 4 Ozark chinquapin 2 x Chinese 2 49 29

'The four American trees \\ere half-SIbs from a female tree 111 a \\oodlot In Rock~ HIlI. CT: Ozark chInquapIns I and 2 were from Russeh Ille. Arkansas. planted 1936 In Hamden. CT Ch111cse chesll1ut I \\as a graft of Luther Burbank's . MIracle'. planted about 1949 111 Hanlden. CT ChInese chestnut 2 \\ as Plant IntroductIOn #703 15 planted 1930 In Hanlden. CT

Table 2. Number of trees with chestnut blight cankers (caused by Cryphonectria parasitical on their trunks and number with Asian chestnut gall wasp (Oryocosmus kuriphilus) galls on terminal branches, in 2006 and 2009. Trees had two different male parents (M 1 and M2) and the female parents were America n chestnuts that were half-sibs. All were planted in North Carolina in 1995.

Male Bl ight cankers on trun ks' Galls on tenm inal branches" 2006 2009 2006 2009

+ - + - 0 1-1 0 ~11 0 1-10 ~11 Ml 17 a 7 a 6 7 2 6 1 a M2 20 16 28 1 5 18 13 25 3 1

'Chesll1ut blIght disease cankers present (+) or absent (-) on trunks: "Wasp gall numbers. 0 no galls detected on branch temlinals, 1 - 10 galls noted on branch temllflals. II or more galls noted on branch terminals

16 101 ~ Ann ual Recor.! Ma rc h 201 1 on weak twigs." Cultivar 'Ginrei' conferred resistance to Ac knowl edgements progeny five times when used as a female parent, and tWice This work was supponed by the US DA Forest Service, when used as a pollen parent. Other cultivars used in crosses and by Mcintire-Stennis grant #631 from the SDA. A pre­ had fewer resistant progeny. The authors did not offer any liminary repon on this work was made at the Workshop on conclusions about genetic control of resistance to gall wasp Chestnut Management in Mediterranean Countries in Turkey infestation. However, Kotobuki said that significantly more in 2007. The assistance of Pamela Sletten dunng all of this offspnng had resistance if the parents were cultivars with work is gratefully acknowledged. good resistance than if the parents were less resistant. Sanor el al. (2009) reponed that cultivar ' Bouche de Betlzac' (a Literature Cited Japanese x European hybrid) showed good resistance to in­ Anagnostakis SL (1998) Chestnuts in GeorgIa. Annll. Repr. festatIon in their tests. one of these cultlvars are available Northern NIII Growers Assoc. 89 :5-14 In our collectIon, and no current information is available about how \\ell the resistance has held up in the presence of Anagnostakis SL, Clark S, McNab H (2009) Preliminary ASian chestnut gall wasp in Japan. repon on the segregation of resIstance In chestnuts to Ill­ festation by oriental chestnut gall \\ asp. Acra Hort. #815 , We expected genes from the Chinese chestnut parents to ISHS, A. Soylu and C. Men eds .. p.33-37 Impan partial resistance to chestnut blight disease to some of the hybrids. This \\ould allow some trees to survive long Cooper WR. Rieske LK (2007) Community associates of enough to be rated for gall wasp resistance. Chinese chest­ an exotic gall maker, Dryocosmlls kunphl/lls, (Hymenop­ nut trees have never been reponed to have any resistance tera: Cynipidae) in eastern onh America. Ann. of rhe to gall \\ asp infestation. Because gall wasp resistance \\ as Enr. Soc. Amer. 100:236-244 observed in Alleghen) and Chinese chinquapins (c. pllm­ Kotobuki K. Machida Y. Sato Y. KaJiura I, Kozono T (1984) Iia and C. henryi) (Anagnostakis, personal observation), Genetics of the resistance to the Chestnut Gall Wasp \\e used male parents that were Chinese chestnut crossed • (Dryocosmlls kunphtills Yasumatsu), harvest date, mean \\ Ith Ozark chinquapin (c. ozarkensls). wluch is a tImber "V ; nut weight, and the characteristics of selected clones of tree (unlike C. punula) with more winter hardiness than chestnut: results of the fourth chestnut breeding program. C henryl and some resistance to chestnut blight disease (m Japanese) BIIII. Fnlll Tree Res. Sm. . 11 :43-53 (Anagnostakis, personal observation). [fthe Ozark chinqua­ Payne JA, Green RA, Lester CD (1976) ew nut pest. an pins had genes for resistance to gall \\ asp infestation In their Oriental Chestnut Gall Wasp in North America. Annll. c)loplasm, the C. ozarkensls x C. molbsslma trees used as Rep. Northern Nllr Growers Assoc. 67 .83 -86 male parents \\ ould have carried these genes, but none of our planted hybrids \\ould have any resistance, since American Rieske LK (2007) Success of an exotic gallmaker, Dryo­ chestnuts (the mother-trees) all appear to be susceptible. If cosmlls /amphllus, on chestnut in the USA : a historical nuclear genes for resistance were dominant, the resistance account. Bull . Euro. and Medlter. PI. Pror. Org. 37: 172- phenotypes should be segregating among the progeny. We 174 would expect half of the progeny to be resistant, if resistance Sartor C. Botta R., Mellano MG. Beccaro GL, Bounous G. \\'as controlled by a single dominant gene; one out of four if Marinoni DT, Quacchia A. Alma A (2009) Evaluation of two dominant genes, or one out of eight if there were three susceptibility to Dryocosmus kunphillls Yasumatsu (Hy­ dominant genes. menoptera: Cynipidae) in Casranea sanva Miller and in Since there was segregation for susceptibility to gall wasp hybrid cultivars. Acra Horr. #815. I HS , A. Soylu and C. mfestation among our surviving hybrids, the genes for re­ Men eds., p289-297 sistance to infestation cannot be cytoplasmic. The numbers tehli R (2003) Oriental chestnut gall wasp found in N.E. of survivors are too small to detennine the exact number of Ohio. The NlIIshell57: 1&19 resistance genes in the male parents. The 28 of the 36 su r­ viving hybrids with good to moderate chestnut blight di sease Stehli R (2006) Oriental Chestnut Gall Wasp in Ohio - an update. The Nurshell60:27 resistance all had few or no galls. New crosses will be made and tested in the future. Larger numbers of progeny will help us detenn ine whether resis­ tance to Asian chestnut gall wasp is simply inherited. If so, that resistance can easily be transferred by breeding to tim­ ber and orchard chestnut types at risk.

1 01 ~ Annual Report, March 2011 17